The invention relates to improvements in rod making machines of the tobacco processing industry, and more particularly to improvements in distributors (also called hoppers) which are utilized in machines for the making of cigarette rods, cigar rods or other types of tobacco-containing rods (hereinafter referred to as cigarete rod making machines) to draw tobacco particles from a magazine and to convert the withdrawn particles into one or more homogeneous streams ready to be trimmed, locally densified and/or otherwise treated or processed prior to conversion into one or more rod-like fillers each of which is ready to be draped into a web of cigarette paper. The resulting cigarette rod(s) is(are) subdivided into plain cigarettes of unit length or multiple unit length.
A distributor normally comprises a magazine which can receive batches of tobacco particles from one or more pneumatic conveyors, at least one elevator conveyor which draws smaller accumulations or batches of particles from the magazine, and an upright duct having an open top for reception of tobacco particles from the elevator conveyor and an open bottom above the carding at the periphery of a driven wheel which receives a continuous carpet of tobacco particles and cooperates with a so-called picker roller to convert the carpet into a shower of tobacco particles. Such particles are intercepted by an endless conveyor which forms a stream ready to be converted into the rod-like filler of a continuous cigarette rod. The homogeneousness or lack of homogeneousness of the carpet of tobacco particles influences the quality of the ultimate products, such as plain cigarettes or filter cigarettes.
Commonly owned U.S. Pat. No. 5,009,238 granted Apr. 23, 1991 to Heitmann for "APPARATUS FOR SUPPLYING FIBROUS MATERIAL TO MACHINES FOR SIMULTANEOUSLY PRODUCING A PLURALITY OF CIGARETTE RODS" discloses a distributor for the simultaneous making of two tobacco rods. The patented distributor employs several gates which are set up to promote the homogeneousness of the tobacco streams formed by the distributor. More specifically, the distributor is designed to enable the duct to effect a more uniform distribution of tobacco particles at the outlet which, in turn, enables the carding of the driven wheel to accumulate a superior (gap-free) carpet of tobacco particles. Such carpet is thereupon processed to form a plurality of discrete streams.
Commonly owned U.S. Pat. No. 4,681,124 granted Jul. 21, 1987 to Hinzmann et al. for "APPARATUS FOR MANIPULATING PARTICLES OF TOBACCO OR FILTER MATERIAL" discloses a distributor with an upright duct the lower end of which includes oscillatable front and rear walls to thus enhance the quality of the carpet of tobacco particles being received and entrained by the carding at the periphery of the driven wheel beneath the duct. The front and rear walls of the lower end portion of the duct are oscillated in the direction of the axis of the rotary wheel.
British patent No. 477,986 (corresponding to U.S. Pat. No. 2,113,514 to Ruau) discloses a tobacco feeding apparatus wherein the carding of the rotary wheel receives tobacco particles from a duct having a bottom portion with a pair of parallel walls which are oscillatable toward and away from each other.
The aforedescribed proposals have been found to bring about some improvements in the consistency of the carpet which is being drawn by the carding of the rotary wheel. However, such undertakings cannot invariably ensure the making of a high-quality (gap-free) carpet which can be converted into one or more homogeneous tobacco streams.